XT10 classic with premium optics Tri-knob CR2 focuser
Catseye + Glatter collimation tools
StarBlast 4.5" & 6"
Round Table Platform
-DannyMy warehouseMy Channel
Quote:Maybe he needs to sq up the focuser.
Quote:...When I go to center my secondary with a cheshire things look as they should...
Quote:...With the secondary centered I can get the three mirror clips in view but when I start to tweak my secondary I start to loose one of the mirror clips...
Quote:Assuming you end up with this view
Quote:...you guessed it correctly. When all looks well and I attempt to center the cross hairs on the center mark things go askew.
Quote:..Jason are you refering to a fore and aft adjustment when you use the word tie and ifso I am to understand the secondary mirror is a little to close to the primary and needs to go forward towards the front of the tube.
Quote:...I will try the best I can to center the secondary with the cheshire. This is done by extending the cheshire very carefully up the focuser with an extension tube.
Quote:I don't like doing it this way but if I can just get halfway close to collimation I can do a star test later and bring it in.
Quote:...The collimation cap offers a much wider view of my efforts. Once this is done I will attempt to put the cheshires cross hair on the primarys center spot.
Quote:Jason, I wonder if you could create a graphic like this one showing the secondary mirror offset downward (toward the six o'clock position) to demonstrate when the user needs to consider realigning the focuser (assuming the spider/secondary mirror are properly centered).
Quote: A second graphic, showing the secondary skewed toward the center of the fov (an ellipse with the centered primary mirror reflection) would demonstrate the other possible "best" alignment with a misaligned focuser.This would help clear up what looks like rotation/offset/tilt combined errors when in fact, the focuser needs to be shimmed/leveled...
Quote:...I am using an extension tube for my cheshire because the cheshire will not incorparate the view I need of the secondary.
Quote:...I am using a moonlite focuser with only .5" travel.
Quote:Today I decided to try collimation with a collimation cap and things have began working out better for me. I know the collimation cap is the weakest link in collimation but so would the registration on the cheshire.
Quote:Today I have been able to center the secondary under the focuser with good results. I am able to see all three primary mirror clips in good relief and center my primary's center doughnut on the collimation cap.
Quote:The rest of this afternoon I have been chasing that same doughnut with the primarys adjusters. I have so far been able to get the doughnut in the center of the silver circle of the collimation cap and eclipsing the the black dot but its not quite there yet.
Quote:I am handicapped in using the cheshire or sight tube because they are not long enough.
Quote:I am building a 12.5" f/4 telescope and using a 3.10" secondary and the tube diameter is 16". Its quite a beast especially with that heavy Coulter mirror of yesterday.
Quote:...I guess I am stuck with the collimation cap until I can find a long sight tube or cheshire to accomadate my needs. Getting that big secondary mirror in the cheshire is just not possibe and thats why I opted later this morning on the collimation cap.
Quote:....Vic I am sorry I am so dense but what do mean by axial alighments.
Quote: ...Vic,Jason tommorrow I plan on using a Helix laser to be sure my primarys optical axis is dead center of my tube. It has a hologram that projects a bullseye. By checking the shadow of the secondary in the bullseye I should be able to tweak the primarys adjuasters to center the primarys optical axis(not my idea as I read this somewere).
Quote:...what do mean by axial alignments.
Quote:...When I'm happy I remove the bottom lid to expose the primary.And often there is very little 'tilting' to do (regarding the secondary).
Quote:...Then again, I put in the cheshire and check the primary. And every time I find that it's a little bit off, but that's because of my inacurate barlow method.
Quote:As a note : I cannot see the six primary mirror clips through the cheshire, not even when it's fully racked in.
Quote:...I know i might be quartered for the next statement but..a laser colli is ( )...
Quote:...Only the barlowed method is reliable.
Quote:...get a cheshire combo tube !!!
Quote:Trouble it is false. The shadow of the secondary is offset if collimation is correct in all respects. (Centering can only be achieved by moving the secondary away from the primary, cancelling the offset that centers the secondary in the sight tube and thus the fully illuminated field).
Quote: ...Vic,Jason when the secondary is centered in the tube bothfore and aft and laterally how much of the primary should be seen in the collimation cap.
Quote:I see my mirror clips that stand proud and I assume I am at the very edge of the primary but to this point I have yet to see it completly in the secondary. Should I move the secondary up a tiny bit to encompass the primary and if so by about how much.